incrementPushStats

Increments the push statistics for a push application by the given push count and total content sum. If there are no push
statistics for this push application, a new entry will be created in storage and will be used as a basis for future
increments.

pushApplicationId - id of the push application that the push statistics correspond to

preferUseCache - specifies whether the cached value of the remaining quota is preferable or not. In the first case (
preferUseCache is equal to true), the method will try to retrieve the remaining quota
from the cache first. If there is no cached value found, a look up in the persistent store will be done. If
preferUseCache is equal to false, the remaining quota will always be retrieved from
the persistent store. Using the cache will generally be a faster operation. Note: Retrieving the remaining quota
from the persistent store can be somewhat inaccurate. Updates to the push statistics in storage are batched and
persisted at a regular interval and so the stats might be slightly off within that interval.